USB: Add parsing of SuperSpeed endpoint companion descriptor.

Allow the xHCI drivers (and any new USB 3.0 drivers) to parse the
SuperSpeed endpoint companion descriptor to find the maximum number of
bulk endpoint streams the endpoint supports.  This is used to calculate
the maximum total number of streams the driver can allocate.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>